1. Field of the Invention
The present invention relates to a solid electrolyte battery having a battery element in which a cathode and an anode are laminated through a solid electrolyte and a method for manufacturing it, and more particularly to a solid electrolyte battery in which the generation of a short-circuit in the cathode is prevented.
2. Description of the Related Art
In recent years, portable electronic devices such as portable telephones or thin electronic devices such as note book type personal computers have been progressively made compact and light. In these circumstances, batteries serving as driving power sources as the electronic devices have played important roles. It has been necessary for the batteries as the driving power sources to be light and efficiently utilize accommodation spaces in the devices in order to realize the compact and light electronic devices. As such batteries, solid electrolyte batteries high in their energy density and output density, more specifically, lithium-ion batteries are most preferable.
The solid electrolyte battery has a coiling type battery element in which a cathode having a cathode composite mixture layer formed by applying a cathode composite mixture on a cathode current collector and an anode having an anode composite mixture layer formed by applying an anode composite mixture on an anode current collector are laminated through a solid electrolyte and the laminated body are coiled in the longitudinal direction, or a zigzag bending type battery element formed in such a manner that the laminated body of a cathode and an anode through a solid electrolyte are bent in a zigzag way.
In the cathode of the battery element provided in the solid electrolyte battery, the end part of the cathode composite mixture layer, that is, the end part at which the cathode composite mixture begins to be applied and the end part at which the application of the cathode composite mixture is finished are lager in their thickness of application of the cathode composite mixture than other parts. Thus, these end parts have large thickness and are brought into swelling states.
However, the swelling parts at the end parts of the cathode composite mixture layer undesirably greatly cause a short-circuit, so that yield is disadvantageously deteriorated upon manufacturing the solid electrolyte battery.
Further, even when a separator is provided between the cathode and the anode, in case the thickness of the separator is very small as low as about 15 μm or smaller, the generation rate of the short-circuit at the end parts of the cathode composite mixture layer will be inconveniently high.